Summary:
Setting the Item nbt tag of projectiles, which determines, which item to render to air doesn’t work. The nbt tag instantly removed, instead of making the item invisible. Affect projectiles are snowballs, eggs, ender pearls, fireballs and small fireballs.

Steps to reproduce:

1. /summon minecraft:snowball ~ ~ ~ {Item:{id:"minecraft:air",Count:1b}} 

   you can change the entity to any other projectile

Observed results:
Projectiles appear with their normal texture.

Expected results:
Projectiles will be invisible.